Gas pressure regulators have a wide variety of industrial applications, including regulating the pressure of compressed air supplied to machinery, equipment and pneumatic tools used in a wide variety of manufacturing and assembly operations. In many industrial applications air is supplied at an unregulated pressure of about 100 to 150 psig. The regulators produce a reduced output pressure which can be varied and is usually in the range of about 10 to 125 psig.
Previously, pressure regulators have been of two general types. In one type, a main valve or variable area orifice is controlled and adjusted by a movable diaphragm subjected to the regulated or secondary output pressure on one side and an adjustable force produced by a spring on the other side. This type of regulator requires a high spring force and spring rate which results in a relatively imprecise regulation of pressure and requires a large control force which makes adjustment of the regulated pressure difficult and time consuming. Typically, for industrial pneumatic tool applications, in use the secondary or output pressure of this regulator varies by about 10 psig from the nominal regulated pressure.
In the other type of pressure regulator, the main valve or variable area orifice is controlled by a diaphragm connected to the main valve and subjected to the secondary or outlet pressure on one side, and a regulated pressure on the other side. This regulated pressure usually is produced by either an orifice and relief valve or a second pilot regulator. To provide precision regulation, this regulated pressure is produced by a pilot regulator with a pilot diaphragm with one face communicating with the inlet of the primary regulator. Both of the diaphragms are continuously bled through very small restricted orifices which are expensive to manufacture, prone to becoming clogged and result in the loss or wasting of considerable compressed gas and generation of considerable noise. This second type of regulator provides more precise control of the outlet pressure which varies by about 3 psig from the nominal regulated pressure. However, in most applications, the manufacturing cost, operating expense and maintenance expense of this type of regulator is prohibitive.